moving common sibling nieces leaf properties up to be... siblings? in a map

 So this is almost harder to describe than show, but we have a big map like object. CSS properties for components are at the leaves, so for instance "button.square.lg.pressed" might have the CSS key/values for the pressed state. But that leads to a lot of duplication, like maybe "button.square.lg.idle" is the same except for the color or something. So we'd like to move the actual properties up to point where every child has them in common, so 

{
 "button": {
  "idle": {
   "margin": "16px 8px",
   "backgroundColor": "white"
  },
  "hover": {
   "margin": "16px 8px",
   "backgroundColor": "lightblue"
  },
  "focus": {
   "margin": "16px 8px",
   "backgroundColor": "darkblue"
  }
 }
}

might become

{
 "button": {
  "idle": {
   "backgroundColor": "white"
  },
  "hover": {
   "backgroundColor": "lightblue"
  },
  "focus": {
   "backgroundColor": "darkblue"
  }
 },
 "margin": "16px 8px"
}

like that.
A coworker basically did the work (using lodash's isObject and isEqual) - here is a codepen using lodash and typescript, the code is 

// import { isObject, isEqual } from '/lodash';

const hasPlainChildren = (obj: any) => {
  for (const key of Object.keys(obj)) {
    const child = obj[key] as any;
    if (!_.isObject(child)) continue;
    for (const childKey of Object.keys(child)) {
      const newChild = (child as any)[childKey];
      if (_.isObject(newChild)) return false;
    }
  }
  return true;
};

const promoteValues = (obj: any, ignoreList: string[]) => {
  const newObj = { ...obj };
  const items = [] as { key: string; value: any; presentIn: string[] }[];
  if (!_.isObject(newObj)) {
    return newObj;
  }
  for (const key of Object.keys(newObj)) {
    const child = (newObj as any)[key];
    if (!_.isObject(child)) continue;
    for (const prop in child) {
      if (_.isObject((child as any)[prop])) continue;
      const valueInSet = items.find(
        (item) => item.key === prop && item.value === (child as any)[prop],
      );
      if (valueInSet) {
        valueInSet.presentIn.push(key);
      } else {
        items.push({
          key: prop,
          value: (child as any)[prop],
          presentIn: [key],
        });
      }
    }
  }
  for (const item of items.filter((item) =>
    _.isEqual(
      item.presentIn,
      Object.keys(newObj).filter((key) => !ignoreList.includes(key)),
    ),
  )) {
    (newObj as any)[item.key] = item.value;
    for (const key of Object.keys(newObj)) {
      const child = (newObj as any)[key] as any;
      if (_.isObject(child)) {
        (child as any)[item.key] = undefined;
      }
    }
  }
  return newObj;
};

export const simplifyObject = (obj: object, ignoreList: string[]) => {
  let newObject = { ...obj } as any;
  if (!hasPlainChildren(newObject)) {
    for (const key of Object.keys(newObject)) {
      if (!_.isObject(newObject[key])) continue;
      newObject[key] = simplifyObject(newObject[key], ignoreList);
    }
  }
  newObject = promoteValues(newObject, ignoreList);
  return newObject;
};
const foo = {
  button: {
    idle: {
      margin: "16px 8px",
      backgroundColor: "white"
    },
    hover: {
    margin: "16px 8px",
    backgroundColor: "lightblue"
  },
  focus: {
    margin: "16px 8px",
    backgroundColor: "darkblue"
  }
}
};

window.time.innerHTML = Date.now(); 
window.before.innerHTML = JSON.stringify(foo, null, ' ');
window.after.innerHTML = JSON.stringify(simplifyObject(foo,[]), null, ' ');

with this bit of HTML to show results:

<pre id="time"></pre>
before:
<pre id="before"></pre>
after:
<pre id="after"></pre>

Haven't really poured over the code but it seems to do the job!